Bump protobuf from 3.13.0 to 3.18.3 in /src/emailservice (#133)

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.13.0 to 3.18.3.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](protocolbuffers/protobuf@v3.13.0...v3.18.3)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/emailservice/requirements.txt

@@ -26,7 +26,6 @@ opentelemetry-api==0.12b0
     #   -r requirements.in
     #   opentelemetry-exporter-zipkin
     #   opentelemetry-instrumentation
-    #   opentelemetry-instrumentation-dbapi
     #   opentelemetry-instrumentation-grpc
     #   opentelemetry-instrumentation-requests
     #   opentelemetry-instrumentation-sqlite3
@@ -36,7 +35,6 @@ opentelemetry-exporter-zipkin==0.12b0
 opentelemetry-instrumentation==0.12b0
     # via
     #   -r requirements.in
-    #   opentelemetry-instrumentation-dbapi
     #   opentelemetry-instrumentation-requests
     #   opentelemetry-instrumentation-sqlite3
 opentelemetry-instrumentation-dbapi==0.12b0
@@ -52,7 +50,7 @@ opentelemetry-sdk==0.12b0
     #   -r requirements.in
     #   opentelemetry-exporter-zipkin
     #   opentelemetry-instrumentation-grpc
-protobuf==3.13.0
+protobuf==3.18.3
     # via grpcio-health-checking
 python-json-logger==0.1.11
     # via -r requirements.in
@@ -62,18 +60,12 @@ requests==2.26.0
     #   opentelemetry-exporter-zipkin
     #   opentelemetry-instrumentation-requests
 six==1.15.0
-    # via
-    #   grpcio
-    #   protobuf
+    # via grpcio
 urllib3==1.26.6
     # via
     #   -r requirements.in
     #   requests
 wrapt==1.12.1
     # via
     #   opentelemetry-instrumentation
-    #   opentelemetry-instrumentation-dbapi
     #   opentelemetry-instrumentation-sqlite3
-
-# The following packages are considered to be unsafe in a requirements file:
-# setuptools